It’s an excruciating dilemma for environmentalists. If the world fails to prevent severe damage from climate change, bringing ecological devastation all around, surely we must use whatever means available to stop it?

Confronted with a climate emergency – an event beyond which there may be no recovery, such as a massive methane release from melting permafrost or the collapse of the West Antarctic ice sheet – surely we will have to throw prudence to the wind and intervene decisively?

When an organization as conservative as the World Bank begins to warn that “we’re on track for a 4°C warmer world marked by extreme heat-waves, declining global food stocks, loss of ecosystems and biodiversity, and life-threatening sea level rise,” a climate emergency begins to look less like idle speculation and more like a forecast.

So within the next decade all citizens will have to take a stance on geoengineering. Before humanity makes what may be its most momentous decision – to use its technological power to take control of the planet’s climate system and regulate it in perpetuity – a long and deep debate should occur. Assuming, of course, that “humanity” will make the decision, rather than the desperate government of a collapsing nation or a rogue billionaire with a messiah complex.

Some geoengineering technologies are relatively benign. Sucking carbon dioxide out of the air is harmless in itself, as long as we can find somewhere safe to bury enormous volumes of it for a thousand years. But each standard-sized coal-fired power plant would need massive air-sucking machinery and six chemical plants, with a footprint of more than 2 square miles, and an additional network of pipes and equipment to transport and bury the waste underground.

The idea of building a vast industrial infrastructure to offset the effects of another vast industrial infrastructure only highlights our unwillingness to confront the deeper causes of global warming: the power of the fossil fuel lobby and the apparent unwillingness of wealthy consumers to make even small sacrifices.

The greater anxieties arise from those system-altering geoengineering technologies designed to intervene in the functioning of Earth’s system as a whole. They include sulphate aerosol spraying, ocean iron-fertilization, and marine cloud brightening.

How confident can we be, even after extensive testing, that the chosen technology will work as planned? After all, ocean fertilization means changing the chemical composition and biological functioning of the world’s oceans, with a view to getting excess carbon dioxide out of the atmosphere and into the deep ocean. In the process it will interfere in marine ecosystems and affect cloud formation in ways we barely understand.

Brightening ocean clouds to increase their reflectivity could be accomplished by building a fleet of special ships to roam the oceans spraying droplets of seawater into the air. But computer models indicate that brightening clouds in one region might bring baffling weather changes on the other side of the globe. Brightening clouds in the South Atlantic, for example, may bring drought to the Amazon. We don’t understand why.

Enveloping Earth in a layer of sulphate aerosols would regulate the amount of solar radiation reaching the planet’s surface. Plant life, already trying to adapt to more carbon dioxide in the atmosphere and perhaps drier soils, would have to deal with reduced sunlight, the basis of photosynthesis. The filter may be effective at cooling the planet, but its effects on weather systems, including the Indian monsoon, is in doubt.

Some of these uncertainties can be reduced by research. Yet if there is one lesson we have learned from ecology, it is that the more closely we look at an ecosystem the more complex it becomes. Now we are contemplating technologies that would attempt to manipulate the grandest and most complex ecosystem of them all – the planet itself. System-altering geoengineering would transform not just the atmosphere but the hydrosphere, the biosphere, and geological processes, too.

The most likely method of climate engineering, sulphate aerosol spraying, is classified as a form of “solar radiation management,” an Orwellian term some have attempted to reframe as “climate remediation.” Yet if the “remedy” were fully deployed to reduce the Earth’s temperature by, say, 1.5°C, it is estimated that at least 10 years of observation would be needed to separate out the effects of the solar filter from other causes of climate variability.

If after five years of dimming the globe, climatic disasters occurred – droughts in India, for example – we would not know whether they were caused by global warming, the solar filter, or natural variability. And if India were suffering while the United States enjoyed milder weather, who would control the temperature gauge?

Engineering the climate is appealing to a powerful strand of Western technological thinking that sees no ethical or other obstacle to total domination of nature. Promethean plans for mastery have always met resistance from those who mistrust human technological overreach. In Earthmasters, I argue that climate engineering is the last battle in a titanic struggle between the Prometheans and those who might be called the Soterians (after the Greek goddess of safety, preservation, and deliverance), with the prize being nothing less than the survival of a liveable planet.

In the end, how we think about geoengineering depends on how we understand the climate crisis. We live in societies predisposed to seek technological answers to social problems. If our failure to cut emissions is due to the power of corporate interests, growth fetishism, and the comfortable conservatism of consumer society, then resorting to geoengineering acts to deflect attention, to avoid facing up to social dysfunction.

As a technofix, climate engineering is in line with existing structures of power and a society based on endless consumption. Yet geoengineering, if it works at all, can only be a provisional response, a path that merely puts off the day of reckoning.